So many variables come into play...
Baynes hit the big time after his confidence rose from his Olympic selection and the Euro League experience added that extra needed to realise his potential, but now he is having to learn a whole new style of play in the NBA D League to get some minutes at that level of competition.
My point is, even a player as talented as say Jeremy Lin had to go and seek extra coaching in China to fix up little issues he had to make it to the top, so if Young wants it bad enough and he has the skill and size, then of course he can play NBL.
It is a matter of getting the stars to align, and of course his efforts and desire to improve in the areas he needs to for the league he wants to play in.
Horses for courses, if you like...